Place a large sauce pot over medium-high heat. Once hot, add the bacon and cook, stirring often, until crispy, about 5 to 8 minutes. Using a slotted spoon, transfer to a plate lined with paper towels and set aside.
Discard all but 1 tablespoon of the bacon grease and add in the onion, garlic and jalapeño. Cook until softened, about 5 minutes. Add in the butter and cook, until melted through. Sprinkle in the flour and cook for about 30 seconds. Stir in the milk and cook until thickened, about 4 to 5 minutes. Season with salt, pepper, pepper flakes, mustard powder and chili powder (and hot sauce if using).
Remove the sauce from the heat and add in the cheeses, stirring until completely melted through. Return to low heat and stir in the broccoli and cooked bacon. Cook for about 5 minutes to warm through and slightly soften the broccoli.
Serve warm with crackers, chips or vegetables. Enjoy!